cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A098360 Multiplication table of the cube numbers read by antidiagonals.

Original entry on oeis.org

1, 8, 8, 27, 64, 27, 64, 216, 216, 64, 125, 512, 729, 512, 125, 216, 1000, 1728, 1728, 1000, 216, 343, 1728, 3375, 4096, 3375, 1728, 343, 512, 2744, 5832, 8000, 8000, 5832, 2744, 512, 729, 4096, 9261, 13824, 15625, 13824, 9261, 4096, 729, 1000, 5832, 13824
Offset: 1

Views

Author

Douglas Stones (dssto1(AT)student.monash.edu.au), Sep 04 2004

Keywords

Examples

			1; 8,8; 27,64,27; 64,216,216,64; ...
		

Crossrefs

Row sums: A145216. - N. J. A. Sloane, May 31 2009

Programs

  • GAP
    Flat(List([2..11],m->List([1..m-1],i->i^3*(m-i)^3))); # Muniru A Asiru, Jun 27 2018
  • Maple
    seq(seq(i^3*(m-i)^3,i=1..m-1),m=2..10); # Robert Israel, Jun 27 2018
  • Mathematica
    With[{s = Range[10]^3}, Table[s[[#]] s[[j]] &[i - j + 1], {i, Length@s}, {j, i}]] // Flatten (* Michael De Vlieger, Jun 27 2018 *)

Formula

G.f. as rectangular array: [xy(1+4x+x^2)(1+4y+y^2)] / [(1-x)^4 * (1-y)^4 ]. - Ralf Stephan, Oct 27 2004, corrected by Robert Israel, Jun 27 2018
a(n) = A003991(n)^3.- Robert Israel, Jun 27 2018

Extensions

More terms from Ralf Stephan, Oct 27 2004
Offset corrected by Robert Israel, Jun 27 2018

A213558 Rectangular array: (row n) = b**c, where b(h) = h^3, c(h) = (n-1+h)^3, n>=1, h>=1, and ** = convolution.

Original entry on oeis.org

1, 16, 8, 118, 91, 27, 560, 496, 280, 64, 2003, 1878, 1366, 637, 125, 5888, 5672, 4672, 2944, 1216, 216, 14988, 14645, 12917, 9542, 5446, 2071, 343, 34176, 33664, 30920, 25088, 17088, 9088, 3256, 512, 71445, 70716, 66620, 57359, 43535
Offset: 1

Views

Author

Clark Kimberling, Jun 17 2012

Keywords

Comments

Principal diagonal: A213559
Antidiagonal sums: A213560
Row 1, (1,8,27,...)**(1,8,27,...): A145216
For a guide to related arrays, see A213500.

Examples

			Northwest corner (the array is read by falling antidiagonals):
1.....16.....118....560.....2003
8.....91.....496....1878....5672
27....280....1366...4672....12917
64....637....2944...9542....25088
125...1216...5446...17088...43535
		

Crossrefs

Cf. A213500.

Programs

  • Mathematica
    b[n_] := n^3; c[n_] := n^3
    t[n_, k_] := Sum[b[k - i] c[n + i], {i, 0, k - 1}]
    TableForm[Table[t[n, k], {n, 1, 10}, {k, 1, 10}]]
    Flatten[Table[t[n - k + 1, k], {n, 12}, {k, n, 1, -1}]]
    r[n_] := Table[t[n, k], {k, 1, 60}]  (* A213558 *)
    d = Table[t[n, n], {n, 1, 40}] (* A213559 *)
    s[n_] := Sum[t[i, n + 1 - i], {i, 1, n}]
    s1 = Table[s[n], {n, 1, 50}] (* A213560 *)

Formula

T(n,k) = 8*T(n,k-1) - 28*T(n,k-2) + 56*T(n,k-3) - 70*T(n,k-4) + 56*T(n,k-5) - 28*T(n,k-6) + 8*T(n,k-7) - T(n,k-8).
G.f. for row n: f(x)/g(x), where f(x) = n^3 + ((n + 1)^3)*x + (-8*n^3 + 6*n^2 + 12*n + 8)*x^2 + (8*n^3 - 18*n^2 + 18)*x^3 - ((n - 2)^3)*x^4 - ((n + 1)^3)*x^5 and g(x) = (1 - x)^8.

A349966 a(n) = Sum_{k=0..n} (k * (n-k))^n.

Original entry on oeis.org

1, 0, 1, 16, 418, 17600, 1086979, 92223488, 10292241540, 1462309109760, 257739952352133, 55188518041440256, 14111052911099343782, 4246668467339066589184, 1485904567816768099571207, 598145009954138900489830400
Offset: 0

Views

Author

Seiichi Manyama, Dec 07 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[0] = 1; a[n_] := Sum[(k*(n - k))^n, {k, 0, n}]; Array[a, 16, 0] (* Amiram Eldar, Dec 07 2021 *)
  • PARI
    a(n) = sum(k=0, n, (k*(n-k))^n);

Formula

a(n) = [x^n] (Sum_{k=0..n} k^n * x^k)^2.
a(n) ~ sqrt(Pi) * n^(2*n + 1/2) / 2^(2*n + 1). - Vaclav Kotesovec, Dec 07 2021

A306548 Triangle T(n,k) read by rows, where the k-th column is the shifted self-convolution of the power function n^k, n >= 0, 0 <= k <= n.

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 2, 1, 0, 0, 3, 4, 1, 0, 0, 4, 10, 8, 1, 0, 0, 5, 20, 34, 16, 1, 0, 0, 6, 35, 104, 118, 32, 1, 0, 0, 7, 56, 259, 560, 418, 64, 1, 0, 0, 8, 84, 560, 2003, 3104, 1510, 128, 1, 0, 0, 9, 120, 1092, 5888, 16003, 17600, 5554, 256, 1, 0, 0, 10, 165, 1968, 14988, 64064, 130835, 101504, 20758, 512, 1, 0, 0
Offset: 0

Views

Author

Kolosov Petro, Feb 23 2019

Keywords

Comments

For n > 0 an odd-power identity n^(2m+1)+1, m >= 0 can be found using the current sequence. The sum of the n-th diagonal of T(n,k) over 0 <= k <= m multiplied by A(m,k) gives n^(2m+1)-1, where A(m,k) = A302971(m,k)/A304042(m,k). For example, consider the case n=4, m=2: the n-th diagonal of T(n, 0 <= k <= m) is {5, 10, 34}, and the m-th row of triangle A(m, 0 <= k <= m) is {1, 0, 30}, thus (3+1)^5 + 1 = 5*1 + 10*0 + 34*30 = 1025.

Examples

			==================================================================
k=    0     1     2     3      4      5     6    7    8    9    10
==================================================================
n=0:  2;
n=1:  2,    0;
n=2:  3,    0,    0;
n=3:  4,    1,    0,    0;
n=4:  5,    4,    1,    0,     0;
n=5:  6,   10,    8,    1,     0,     0;
n=6:  7,   20,   34,   16,     1,     0,    0;
n=7:  8,   35,  104,  118,    32,     1,    0,   0;
n=8:  9,   56,  259,  560,   418,    64,    1,   0,   0;
n=9:  10,  84,  560, 2003,  3104,  1510,  128,   1,   0,   0;
n=10: 11, 120, 1092, 5888, 16003, 17600, 5554, 256,   1,   0;   0;
...
		

Crossrefs

Nonzero terms of columns k=0..5 give: A000027, A000292, A033455, A145216, A145217, A145218.
Partial sums of columns k=1..2 give: A000332, A259181.

Programs

  • Mathematica
    f[m_, s_] := Piecewise[{{s^m, s >= 0}, {0, True}}];
    F[n_, m_] := Sum[f[m, n - k]*f[m, k], {k, -Infinity, +Infinity}];
    T[n_, k_] := F[n - k, k];
    Column[Table[T[n, k], {n, 0, 12}, {k, 0, n}], Left]

Formula

f(m, s) = s^m, if s >= 0;
f(m, s) = 0, otherwise.
F(n,m) = Sum_{k} f(m, n-k) * f(m, k), -oo < k < +oo;
T(n,k) = F(n-k, k).

Extensions

Edited by Kolosov Petro, Mar 13 2019
Showing 1-4 of 4 results.